Planform alignment is used in the design of many stealth, or “Low Observable” (LO) (i.e. low detectability by radar systems), aircraft. Planform alignment involves using a small number of surface orientations in the shape of the structure of the aircraft. For example, leading and trailing edges of the aircraft wing, tail surfaces of the aircraft, and surface of other aircraft structures (such as intakes and apertures) may be set to be the same angle. This is done to so that the aircraft reflects radar signals that are detectable only in very specific directions relative to the aircraft, rather than returning a radar signal that may be detected at many different angles.
LO aircraft may be used to carry payloads. Payloads tend to be carried by LO aircraft in internal storage bays. This tends to reduce the radar signature of the payload and maintain the low radar visibility properties of the aircraft.
Deployment of payloads by LO aircraft commonly involves the opening and closing of powered doors on an underside of the aircraft. Such opening and closing of powered doors may be performed while the aircraft is travelling at high speeds.